In a conventional DC breaker for breaking DC (direct-current) electric path, it has been mainly adopted the DC breaking method based on current-limiting type or vibration-type. As for its opening/closing mechanism, it has been used the mechanical contact or the contactless switch of semiconductor (e.g., Japan patent application laid-open No. 2006-32077).
According to the DC breaker which uses the semiconductor contactless switch for the opening/closing mechanism, it can break the electric path without occurring the arc. However, for such the DC breaker, a commutation means such as a snubber circuit should be provided for the purpose of suppressing the generation of the surge voltage resulting from the cutting phenomenon. Even more particularly, the mechanical contact was often necessary for the purpose of secure energization and disconnecting (e.g., Japan patent application laid-open no. 2004-22525).
In recent years, DC breaker has been used in the DC electric path of the electric vehicle or in the DC electric path of the indoor DC distribution system. It has been demanded a DC breaker with: (1) high breaking capacity to the direct current; (2) compact size; (3) enhanced safety; (4) small sound at the time of acting the contacts; and (5) high contact reliability.